The use of Ventricular Assist Devices (VAD) in therapy for end stage heart disease patients is becoming a clinical reality. A new generation of compact implantable rotary VAD's are being developed to supplant the current generation of bulky pusher-plate VAD's. Control schemes for the rotary pumps must be compatible with physiologic needs. The objective of this proposed program is the development of a control scheme that (1) is sensitive to filing pressure thus mimicking the Starling response, (2) utilizes pump motor parameters for optimal flow control without causing inflow suction, and (3) combine these two control schemes as redundant algorithms for rotary blood pump operation in either univentricular, biventricular, or total heart operation. The use of the pump motor parameters for flow control provides a significant added benefit without the need for an additional sensor, providing a complementary physiologic control for the VAD in addition to pressure control. The Phase I program will focus on the development of the motor parameter control scheme to demonstrate stable operation under various physiologic conditions in in vivo studies. PROPOSED COMMERCIAL APPLICATION: There are potentially 70,000 end stage heart disease patients that die annually who can be helped by a compact ventricular assist device. Only 2300 of these subjects are receiving transplantation due to the shortage of donor hearts. An implantable ventricular assist device that is physiologically responsive with simple control schemes can not only save lives but can provide a decent quality of life to the recipient.